Private Named Parameters

[munificent]

This is the tracking issue for the Private Named Parameters proposal.

The proposal makes it easier to initialize and declare private instance fields using named constructor parameters. It addresses #2509 and turns code like this:

class House {
  int? _windows;
  int? _bedrooms;
  int? _swimmingPools;

  House({
    int? windows,
    int? bedrooms,
    int? swimmingPools,
  })  : _windows = windows,
        _bedrooms = bedrooms,
        _swimmingPools = swimmingPools;
}

Into this:

class House {
  int? _windows;
  int? _bedrooms;
  int? _swimmingPools;

  House({this._windows, this._bedrooms, this._swimmingPools});
}

The proposal harmonizes with (and in a couple of places mentions) the primary constructors proposal. When combined with that proposal, the above example becomes:

class House({
  var int? _windows,
  var int? _bedrooms,
  var int? _swimmingPools,
});

Without this proposal, the example here wouldn't be able to use a primary constructor at all without giving up either privacy on the fields or named parameters in the constructor.

[Mike278]

(I think that last example is meant to be

class House({
  int? _windows,
  int? _bedrooms,
  int? _swimmingPools,
});

)

[munificent]

Oops, you're almost right. Fixed, thanks!

[reidbaker]

Consider adding examples of what it looks like to call the new functions.

[munificent]

Oh, good point. Added one to this in-progress PR: #4468